1. Technical Field
This invention generally describes a method for introducing dopants into a semiconductor device. More specifically this invention describes a method for diffusing dopants into a substrate from a doped germanium oxide sacrificial layer on a semiconductor substrate.
2. Description of Relevant Art
The processing of a semiconductor, such as a CMOS dual work function device, typically requires doping p+ or n+ dopants into the semiconductor substrate. A patent to Frenette et al., in U.S. Pat. No. 5,770,490, entitled "Method for Producing Dual Work Function CMOS Device" describes the introduction of a dopant from a solid source, involving deposition of a solid layer containing the dopant onto the semiconductor substrate, then diffusing the dopant from the layer into the substrate by heating.
Both silicon dioxide and germanium solid sources have heretofore used strong acids to remove the silicon dioxide or germanium after the diffusion of the dopant into the semiconductor. Unfortunately, etching with strong acids may result in the removal of the silicon dioxide gate oxide and silicon dioxide used to fill standard isolation structures. This may provide paths for charge leakage between regions of different conductivity, resulting in semiconductor device degradation and failure.